改进的输出系数法在农业污染源估算中的应用

农业污染源是非点源污染的重要来源,了解农业污染源现状是研究流域非点源污染的前提.该文考虑了降雨和地形特征对污染物迁移的损失,并给出了降雨与地形特征对流域农业源污染损失系数的确定方法,研究了改进的输出系数模型.将改进的输出系数模型应用于鄱阳湖流域的4个小区域内,并分别计算4个小流域的降雨和地形特征影响因子,对各种污染物输出系数进行率定和验证,使改进后的输出系数模型更符合农业源污染物运动机理,通过计算发现,部分模拟精度有所提高,并得到了一组适合鄱阳湖流域农业源非点源污染物的输出系数,将其应用到整个鄱阳湖流域的农业源污染物的快速估算,为鄱阳湖流域非点源污染控制提供了科学依据.     

GIS在九龙江流域农业非点源污染信息数据库建立中的应用以五川小流域为例

运用GIS软件MapInfo、ARC/INFO工作站和ArcView3.2建立五川小流域的农业非点源污染信息数据库,包括小流域边界、水系、土地利用现状图及地形图等.利用五川小流域等高线、高程点制作TIN,建立流域数字高程模型(DEM),并在DEM的基础上进行表面分析,提取坡度、坡向、坡长等.运用ArcView的水文分析模块模拟流域的地表水网分布、水网密度.为五川流域农业非点源污染模拟研究提供了基础数据平台,为九龙江流域农业非点源污染研究提供经验借鉴.     

基于SWAT模型的流域非点源污染模拟

利用SWAT(soil and water assessment tool)模型,在GIS技术支持下,通过构建模型所需的空间数据库和属性数据库,以黑龙江蚂蚁河流域为研究区域进行流域非点源污染的模拟研究.分别在时间和空间尺度上对研究区域非点源污染负荷分布进行分析,识别出非点源污染严重的区域及其影响因素.结果表明:在时间尺度上,非点源污染物负荷与降雨量和径流量有较强的相关关系;在空间尺度上,流域西南部地区非点源污染较为严重;不同土地利用类型的非点源污染负荷不同,耕地的非点源污染单位面积负荷最高,疏林地次之,林地等其他土地利用类型的单位面积负荷较小.     

基于改进单位线法的非点源污染负荷估算

Verworn于1978年首次将水文单位线引用到非点源污染负荷估算中,根据实测的污染物浓度、降雨和径流资料提出了定量计算非点源污染负荷的时段单位线——特征污染单位线CPG.该方法在实际应用中,特征污染单位线的推求存在困难,合轴相关图的精度也是该方法的主要制约因素.本文在分析该方法估算非点源污染不足之处的基础上,对其进行了改进,即将降雨量、施肥量、干期时间和场次降雨距离施肥后的时间4个影响非点源污染负荷产生的主要因素作为污染负荷单位线模型的输入,通过分析这4个因素对污染负荷浓度的影响,基于2003—2007年柴河水库流域72场降雨-产流-产污过程建立了相关关系,并类比于水文单位线法推求出了污染负荷浓度单位线.将获得的污染负荷浓度单位线应用于预测柴河水库流域2008—2009年污染过程,模拟得到的2008和2009年流域出口断面总磷质量浓度过程与实测过程纳什效率系数分别达到0.49和0.70.结果表明,改进后的单位线法估算非点源污染具有一定可靠性.     

基于水文水质资料的非点源输出系数模型参数确定方法及其应用

非点源污染模型是目前开展非点源污染研究的主要手段.针对非点源污染模型中的输出系数模型,提出了一种基于历史水文水质资料的参数确定方法.该方法通过在研究区中筛选若干个小流域,根据污染物质量守恒原则,得到各营养源的输出系数.该方法对长江上游2000年的总氮(TN)负荷模拟值为156.19万t,其与实际监测值的相对误差为21.90%,这对于长江上游这样的超大流域而言,模拟精度在可接受范围内.本文提出的参数确定方法简便可行,对参数要求低,且精度较好,适合于对我国非点源污染监测资料缺乏地区以及大中尺度流域的非点源污染负荷研究,因此具有其理论和现实意义.     

基于SWAT的涟水河上游流域非点源污染模拟

以涟水河娄底水文站上游流域为研究区域,应用SWAT模型对该区域的径流、泥沙及非点源氨氮、总磷污染负荷进行模拟计算.将1998年设置为模型启动期,即＂模型预热＂,利用娄底水文站1999～2002年的实测月径流、氨氮及总磷的实测数据进行模型参数确定,运用2003～2005年实测的月径流、氨氮及总磷数据对调参后的模型进行模型验证,验证结果表明模型基本合理可行,可用于涟水河上游流域的非点源污染模拟计算.运用率定后的模型,去除点源污染,重新进行模拟得到最终的非点源污染氨氮、总磷.根据模拟结果对该区域的径流、泥沙、氨氮及总磷污染负荷的时空分布特点进行了分析,为涟水河娄底水文站上游流域非点源污染的综合防治规划提供了参考和依据.     

“撂荒地”影像特征分析及信息提取——以右玉县牛心堡乡为例

耕地撂荒严重影响了我国粮食产量,成为近20年来耕地利用中出现的重大问题.多光谱遥感具有数据获取范围广、速度快等特点,在国土资源研究中具有相当大的潜力和优势.为提取和识别撂荒地,研究采用2010—2014年各年份的4—10月多光谱遥感数据Modis/Terra的NDVI数据产品和2014年6月份Landsat 8遥感影像数据,生成撂荒地、林地、耕地类型采样点的NDVI时间序列曲线,利用时间序列曲线来表征撂荒地、林地及耕地的生命周期特征,结合3种覆被类型的生命周期特征及其NDVI曲线特征,对3种覆被NDVI曲线变化趋势进行对比分析,从而区分撂荒地、林地、耕地,以达到识别撂荒地的目的.结合Landsat 8遥感影像判读和野外考察验证样本,最后对遥感影像进行判读,分析撂荒地的光谱、纹理、形状及位置特征,确立撂荒地解译标志,运用ArcGIS 10.2平台实现撂荒地信息提取.结果表明,运用多光谱遥感技术能够很好地提取撂荒地,提取撂荒地精度达到86%.因此,多光谱遥感技术在撂荒地识别研究中具有相当的可行性.     

涟水流域非点源污染特征

依托GIS软件平台,将SWAT模型应用于湘江支流涟水流域,对涟水流域径流、泥沙及非点源氨氮、总磷污染负荷进行模拟计算.研究结果表明,基于SWAT模型的涟水流域非点源污染模拟是可行的.通过统计分析揭示了涟水流域非点源污染的时空分布规律;通过对比不同施肥水平和不同时期土地利用情景下非点源污染负荷,揭示了施肥水平及土地利用对...     

“两湖”流域农业非点源污染现状与对策

分析了"两湖"流域的农业非点源污染的现状与污染源种类的来源,并针对"两湖流域"农业非点源污染的特征提出了农业非点源控制对策。     

基于输出系数模型的清水河上游农业非点源污染负荷估算

结合调查资料和GIS技术,采用Johnes经典输出系数模型估算2000、2005、2010、2015年清水河上游流域总氮（TN）、总磷（TP）农业非点源污染负荷,并分析其时空变化特征和污染来源。结果表明,四个时期TN、TP的污染输出负荷均呈明显的下降趋势,且前者是后者的9.2~9.8倍;不同污染源类型对TN、TP负荷贡献率的影响规律相似,且土地利用是最关键的影响因素,表现为耕地>草地>林地。从空间变化趋势上,TN、TP的污染负荷强度分布特征相似：整体分布不均,高负荷区集中分布在清水河支流水系两岸坡度较小的平原和丘陵区,低负荷区主要分布在耕地较少的水源涵养区,且TN的负荷强度是TP的10倍左右。分别从土地利用、禽畜养殖和农村生活等角度分析其污染来源,结果表明耕地,尤其是蔬菜等经济作物种植是农业非点源污染的主要来源,禽畜养殖及居民生活是非点源污染的重要组成部分。     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.     

Tracking data management using topology of moving object database system for moving object constrained trajectory in LBS application

Advances in wireless technologies and positioning technologies and spread of wireless devices, an interest in LBS (Location Based Service) is arising. To provide location based service, tracking data should have been stored in moving object database management system (called MODBMS) with proper policies and managed efficiently. So the methods which acquire the location information at regular time intervals then, store and manage have been studied. In this paper, we suggest tracking data management techniques using topology that is corresponding to the moving path of moving object. In our techniques, we update the MODBMS when moving object arrived at a street intersection or a curved road which is represented as the node in topology and predict the location at past and future with attribute of topology and linear function. In this technique, location data that are corresponding to the node in topology are stored, thus reduce the number of update and amount of data. Also in case predicting the location,because topology are used as well as existing location information, accuracy for prediction is increased than applying linear function or spline function.